Tunnel or portal scanner and method of scanning for automated checkout

ABSTRACT

Systems and methods for data reading, which in one example configuration is directed to an automated optical code data reader in the form of a tunnel or portal scanner having an open architecture configured with front and rear inverted U-shaped arches, a plurality of cameras (some or most of which have multiple fields of view) in each of the arches for reading the top live sides of an item being passed by a conveyor through a read region formed by the arches, and a bottom reader including one or more cameras under the conveyor for reading a bottom side of the item through a gap in the conveyors as the item is passed over the gap. Also disclosed are specific imaging schemes for providing effective views of the items with a minimum number of cameras.

RELATED APPLICATION DATA

This application is a continuation of U.S. application Ser. No.13/357,356 filed Jan. 24, 2012, U.S. Pat. No. 8,716,561 which claimspriority to U.S. provisional application No. 61/435,777 filed Jan. 24,2011, hereby incorporated by reference.

BACKGROUND

The field of the present disclosure relates to systems and methods foritem checkout and in certain aspects to retail checkstands or othercheckout stands (e.g., a parcel distribution station) that incorporatedata readers and other electronic devices. The field of the presentdisclosure further relates generally to data reading devices, and moreparticularly to automated devices by which items are conveyed, typicallyon a conveyor, through a read zone of the data reader by which the itemsare identified such as, for example, by reading optical codes or RFID(radio frequency identification) tags on the items.

Data reading devices are used to obtain data from optical codes orelectronic tags (e.g., RFID tags), or use image recognition to identifyan item. One common data reader device is an RFID reader. Another commondata reader device is an optical code reader. Optical codes typicallycomprise a pattern of dark elements and light spaces. There are varioustypes of optical codes, including linear or 1-D (one-dimensional) codessuch as UPC and EAN/JAN barcodes, 2-D (two-dimensional codes) such asMaxiCode codes, or stacked codes such as PDF 417 codes. For convenience,some embodiments may be described herein with reference to capture of1-D barcodes, but the embodiments may also be useful for other opticalcodes and symbols or objects.

Various types of optical code readers, also known as scanners, such asmanual readers, semi-automatic readers and automated readers, areavailable to acquire and decode the information encoded in opticalcodes. In a manual reader (e.g., a hand-held type reader, afixed-position reader), a human operator positions an object relative tothe reader to read the optical code associated with the object. In asemi-automatic reader, either checker-assisted or self-checkout, objectsare moved usually one at a time by the user into or through the readzone of the reader and the reader then reads the optical code on theobject. In an automated reader (e.g., a portal or tunnel scanner), anobject is automatically positioned transported through the read zone viaa conveyor) relative to the reader, with the reader automaticallyreading the optical code on the object.

One type of data reader is referred to as a flying spot scanner whereinan illumination beam is moved (i.e., scanned) across the barcode while aphotodetector monitors the reflected or backscattered light. Forexample, the photodetector may generate a high voltage when a largeamount of light scattered from the barcode impinges on the detector, asfrom a light space, and likewise may produce a low voltage when a smallamount of light scattered from the barcode impinges on thephotodetector, as from a dark bar. The illumination source in flyingspot scanners is typically a coherent light source, such as a laser orlaser diode, but may comprise a non-coherent light source such as alight emitting diode. A laser illumination source may offer advantagesof higher intensity illumination which may allow barcodes to be readover a larger range of distances from the barcode scanner (large depthof field) and under a wider range of background illumination conditions.

Another type of data reader is an imaging reader that employs an imagingdevice or sensor array, such as a CCD (charge coupled device) or CMOS(complementary metal oxide semiconductor) device. Imaging readers can beconfigured to read both 1-D and 2-D optical codes, as well as othertypes of optical codes or symbols and images of other items. When animaging reader is used to read an optical code, an image of the opticalcode or portion thereof is focused onto a detector array. Though someimaging readers are capable of using ambient light illumination, animaging reader typically utilizes a light source to illuminate the itembeing read to provide the required signal response in the imagingdevice. A camera is typically a combination of a lens and an imagingdevice/sensor array, but the terms imager and camera will be usedsomewhat interchangeably herein.

An imager-based reader utilizes a camera or imager to generateelectronic image data, typically in digital form, of an optical code.The image data is then processed to find and decode the optical code.For example, virtual scan line techniques are known techniques fordigitally processing an image containing an optical code by lookingacross an image along a plurality of lines, typically spaced apart andat various angles, somewhat similar to the scan pattern of a laser beamin a laser-based scanner.

Imager-based readers often can only form images from oneperspective—usually that of a normal vector out of the face of theimager. Such imager-based readers therefore provide only a single pointof view, which may limit the ability of the reader to recognize anoptical code in certain circumstances. For example, because the scan orview volume of an imager in an imager-based reader is typically conicalin shape, attempting to read a barcode or other image in close proximityto the scanning window (reading “on the window”) may be less effectivethan with a basket-type laser scanner. Also, when labels are orientedsuch that the illumination source is reflected directly into the imager,the imager may fail to read properly due to uniform reflection washingout the desired image entirely, or the imager may fail to read properlydue to reflection from a textured specular surface washing out one ormore elements. This effect may cause reading of shiny labels to beproblematic at particular reflective angles. In addition, labelsoriented at extreme acute angles relative to the imager may not bereadable. Lastly, the label may be oriented on the opposite side of thepackage with respect to the camera view, causing the package to obstructthe camera from viewing the barcode.

Thus, better performance could result from taking images from multipleperspectives. A few imager-based readers that generate multipleperspectives are known. One such reader is disclosed in U.S. Pat. No.7,398,927 which discloses an embodiment having two cameras to collecttwo images from two different perspectives for the purpose of mitigatingspecular reflection. U.S. Pat. No. 6,899,272 discloses one embodimentthat utilizes two independent sensor arrays pointed in differentorthogonal directions to collect image data from different sides of apackage. Multiple-camera imager-based readers that employ spatiallyseparated cameras require multiple circuit boards and/or mountinghardware and space for associated optical components which can increasethe expense of the reader, complicate the physical design, and increasethe size of the reader. Improved multi-camera systems are disclosed inU.S. Published Application Nos. US-2010-0163626, US US-2010-0163627, andUS-2010-0163628.

The present inventors have, therefore, determined that it would bedesirable to provide an improved imager-based reader and an improvedtunnel or portal scanner system for automated checkout.

BRIEF DESCRIPTION OF THE DRAWINGS

Understanding that drawings depict only certain preferred embodimentsand are not therefore to be considered to be limiting in nature, thepreferred embodiments will be described and explained with additionalspecificity and detail through the use of the accompanying drawings inwhich:

FIG. 1 is a front top isometric view of a checkout system including atunnel or portal scanner according to a preferred embodiment, installedon a checkstand, as viewed from the upstream side of the conveyor.

FIG. 2 is a rear top isometric view of the tunnel scanner of FIG. 1.

FIG. 3 is a partially exploded isometric view of the scanner of FIGS.1-2.

FIG. 4 is a front side isometric view of the scanner of FIG. 1 showingimage views from the right side legs.

FIG. 5 is a front side isometric view of the scanner of FIG. 1 showingimage views from the left side legs.

FIG. 6 is a top plan view of the scanner of FIG. 1 showing image viewsfrom the left and right side legs.

FIG. 7 is a front side isometric view of the scanner of FIG. 1 showingimage views of the rear left side leg.

FIG. 8 front side elevation view of the scanner of FIG. 1 showing imageviews of the rear left side leg.

FIG. 9 is a top plan view of the scanner of FIG. 1 showing image viewsof the rear left side leg.

FIG. 10 is a diagrammatic front side isometric view of the optics setfor forming the image views of the rear left side leg of FIGS. 7-9.

FIG. 11 is a detail of the optic set of FIG. 10 illustrating the lowerimage view.

FIG. 12 is a detail of the optic set of FIG. 10 illustrating the upperimage view.

FIG. 13 is a right side elevation view of the optic set of FIG. 11illustrating the lower image view.

FIG. 14 is a right side elevation view of the optic set of FIG. 12illustrating the upper image view.

FIG. 15 is a top view of the optic set of FIG. 11 illustrating the lowerimage view.

FIG. 16 is a top view of the optic set of FIG. 12 illustrating the upperimage view.

FIG. 17 is a front side isometric view of the scanner of FIG. 1 showingimage views from the rear arch top section.

FIG. 18 is a front side isometric view of the scanner of FIG. 1 showingimage views from the front arch top section.

FIG. 19 is a rear isometric view of the scanner of FIG. 1 (with sidelegs and rear arch removed) showing image views from the front arch topsection.

FIG. 20 is a front side elevation view showing the image views of thefront arch top section of FIG. 19.

FIG. 21 is a left side diagrammatic view showing the optic set and imageviews of the front arch top section of FIG. 19.

FIG. 22 is a detailed view of the optic set of the front arch topsection of FIG. 21.

FIG. 23 is a rear side isometric view of the scanner of FIG. 1 showingimage views from the bottom reader through the conveyor gap.

FIG. 24 is a diagrammatic isometric view of bottom reader of FIG. 23with the arch sections of the tunnel scanner removed.

FIG. 25 is a diagrammatic side view of the optic set of the bottomreader of 24.

FIG. 26 is a detailed view of a portion of FIG. 25.

FIG. 27 is a diagrammatic front side isometric view of part of an opticset of the bottom reader.

FIG. 28 is a side view of the optic set of FIG. 24.

FIG. 29 is a rear side elevation view of part of the optic set of FIG.24.

FIG. 30 is a top plan view of part of the optic set of FIG. 24.

FIG. 31 is a diagram of the imagers for the optic sets of the bottomreader.

FIG. 32 is an isometric view of an alternate tunnel or portal scanner.

FIG. 33 is a rear side elevation view of the rear arch section of thescanner of FIG. 1 showing illumination sets in the left side leg and topsection.

FIG. 34 is a right side elevation view of the scanner of FIG. 1 showingillumination sets in the rear arch left side leg and rear arch topsection.

FIG. 35 is a partial view, on an enlarged scale, of the top section ofthe rear arch section of FIG. 33 showing details of top sectionillumination optics.

FIG. 36 is a right side view detail of FIG. 35 illustrating details ofthe illumination set for the scanner of FIG. 1 according to a preferredembodiment.

FIG. 37 is a rear side elevation view of the rear arch section of thescanner of FIG. 1 illustrating a first group of illumination sets in theleft side leg of the rear arch.

FIG. 38 is a right side elevation view of the first group ofillumination sets in the rear arch left side leg of the scanner of FIG.1.

FIG. 39 is a top plan view of the first group of illumination sets inthe left side leg of the rear arch section.

FIG. 40 is a rear side elevation view of the rear arch sectionillustrating a second group of illumination sets in the left side leg ofthe rear arch section.

FIG. 41 is a right side elevation view of the second group ofillumination sets in the rear arch left side leg.

FIG. 42 is a top plan view of the second group of illumination sets inthe rear arch left side leg.

FIG. 43 is a diagram of the bottom reader illumination of the scanner ofFIG. 1 according to a preferred embodiment.

FIG. 44 is a schematic of an example processing system architecture forthe scanner of FIG. 1.

FIG. 45 is a flow chart of a side scanner and top scanner decodeprocessor algorithm according to an embodiment.

FIG. 46 is a flow chart of a bottom scanner decode processor algorithmaccording to an embodiment.

FIG. 47 is a flow chart of a light curtain processor algorithm accordingto an embodiment.

FIG. 48 is a flow chart of an interconnect processor algorithm accordingto an embodiment.

FIG. 49 is a flow chart of a correlation processor algorithm accordingto an embodiment.

FIG. 50 is an isometric view of a tunnel or portal scanner showing avertical object sensor system of an object measurement system accordingto one embodiment.

FIG. 51 is a side elevation cross-sectional view of the vertical objectsensor system of FIG. 50.

FIG. 52 is a vertical object sensor system of the object measurementsystem according to another embodiment.

FIG. 53 is an isometric view of a lateral object sensor system of theobject measurement system according to one embodiment.

FIG. 54 is an isometric view of the lateral object sensor systemaccording to or one embodiment.

FIG. 55 is a side elevation view of the lateral object sensor system ofFIG. 54.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to the above-listed drawings, this section describesparticular embodiments and their detailed construction and operation.The embodiments described herein are set forth by way of illustrationonly and not limitation. It should be recognized in light of theteachings herein that there is a range of equivalents to the exampleembodiments described herein. Most notably, other embodiments arepossible, variations can be made to the embodiments described herein,and there may be equivalents to the components, parts, or steps thatmake up the described embodiments.

For the sake of clarity and conciseness, certain aspects of componentsor steps of certain embodiments are presented without undue detail wheresuch detail would be apparent to those skilled in the art in light ofthe teachings herein and/or where such detail would obfuscate anunderstanding of more pertinent aspects of the embodiments.

In some embodiments, an image field of an imager may be partitioned intotwo or more regions, each of which may be used to capture a separateview of the view volume. In addition to providing more views thanimagers, such embodiments may enhance the effective view volume beyondthe vim volume available to a single imager having a single point ofview.

FIGS. 1-3 illustrate a scanner 100 installed at a checkstand 5 such asmay be used at a high-volume retail establishment such as a grocerystore or big-box store. The checkstand 5 includes a base or stand 7 witha conveyor configuration with a front end section 11 and a rear endsection 12. The conveyor section front end 11 has a feed-in or shelfportion 13 on which items may be laid prior to and in preparation forplacing on the front conveyor section 15. The items are transported tothe scanner 100 and through the read volume or read region generallydefined by the confines of the front and rear scanner arches 110, 120and the surfaces of the conveyor sections 15, 16. It is noted that thereis a gap between the input or entry conveyor 15 and the exit conveyor 16as will be described in more detail below. The input conveyor 15 may bedescribed as on the upstream side of the scanner 100 and the exitconveyor 16 may be described as being on the downstream side of thescanner 100. After passing through the scanner 100, items are depositedby the exit conveyor 16 onto an optional roller or bagging area 17 wherethey are boxed, bagged or loaded onto a cart for removal by thecustomer. The lower section of the stand 7 is shown with a bottom ofbasket (BOB) detector 9 that detects items on the bottom shelf of agrocery basket. Such detection may be used to alert the customer and/orstore personnel or to otherwise process items that are either large orbulky or potentially forgotten and left on the bottom shelf of thegrocery basket/cart.

For general purposes of discussion, an item 20 (typically bearing abarcode to be scanned) is represented by a rectangular shaped six-sidedpolyhedron, such as a cereal box (hereinafter referred to as abox-shaped item or object) that may be passed through a read region of adata reader, such as for example the data reader 100 installed in acheckout stand 5 at a retail store (e.g., a supermarket). As to thedescription of the following embodiments, it should be understood thatcertain capabilities of the data reader 100 will be described withrespect to reading sides of the box-shaped object 20 and that a checkoutstand and conveyor described is an example transport structure for thecheckstand discussed herein and should not be considered as limiting.The transport systems are generally described with respect to belt-typeconveyor, but other conveyor/transport systems may be employed such as:inclined slides, vibratory conveyors, roller conveyors, turntables,blower systems (the items driven along a surface via a blower),combinations thereof, or other suitable transport systems.

For convenience of description, referring to FIG. 1, this box-shapedobject 20 may be described with respect to its direction of travel 22relative to the ability of the data reader 100 to read certain of thesides of the box-shaped object 20 being passed (as moved by theconveyors 15, 16) through the read volume defined by the front and rearscanner arches 110, 120 and the surfaces of the conveyors 15, 16.Referring to the orientation as illustrated, the box-shaped object 20may be described as having a top side 26, a bottom side 28, and fourlateral sides 30, 32, 34, and 36. The lateral sides may be referred toas the leading (or front lateral) side 30 (the side leading the objectas it is passed through the read region), the trailing (or rear lateral)side 32 (the trailing side of the object as it is passed through theread region), the checker (or left lateral) side 34 (due to itsproximity to a checkout clerk 38), and the customer (or right lateral)side 36 (due to its proximity to a customer 40). Since a use of thistunnel or portal scanner, in a preferred application, is to enableself-checkout, no checkout clerk may be required and the customer oruser/operator may operate the scanner 100 from either side. Thearbitrary side definitions are merely given to provide a frame ofreference to facilitate written description. For example, the right andleft sides shall be used with reference to the box 20. The customer side36 or right lateral side may alternatively be described as a sideoriented generally vertically facing the customer 40. The checker side34 or left lateral side may alternatively be described as the sidefacing opposite the customer side 36. The front and rear lateral sidesmay be described as being disposed to one side of the arch legs in adirection perpendicular to the item direction 22.

The scanner 100 includes a front arch section 110 and a rear archsection 120. Though there may be some differences in the internaloptical components housed within the arch sections, the external archsections are preferably identical configurations. As shown in FIG. 3,the arch sections 110 and 120 are preferably attached to anunderstructure 135 for mounting to the counter section 10. Further asshown in FIG. 3, the under conveyor optics, as will be described in moredetail below, are housed in a sliding drawer section 130 that slides outfrom the checkstand base 7 and is slidably mounted to the chassissection 135 on rails 137. Thus, all the optics, namely the optics infront arch section 110, rear arch section 120, and drawer section 130are mounted and thus aligned on a common chassis 135. Front arch section110 includes the right leg or post section 112 and the left leg or postsection 114 such that when installed/assembled on the chassis 135 extendupward and diagonally forward or upstream relative to the conveyor witha front arch top section or cross arm 116 spanning between the arch legsections 112, 114, thus forming an inverted U-shaped structure. Thefront arch top section 116 includes an enlarged or extension portion 118to provide for enlarged interior space accommodating internal opticswithin the enlarged volume. The front arch sections 112, 114, 116 areessentially hollow for accommodating optics and other components.Similarly, the rear arch section 120 comprises an inverted U-shapedhousing structure including a rear arch first leg section 122, a reararch second leg section 124 and a rear arch top section or cross arm 126spanning therebetween. The front arch section 110 and the rear archsection 120 are positioned back-to-back with the front arch section 110being slanted forward and the rear arch section 120 being slantedrearward.

Advantageously over prior designs of a large rectangular enclosedbox-shaped tunnel, the arch sections 110, 120 may be disassembled andstacked in a more compact package thus saying on shipping, staging andstorage costs.

When assembled, the arch sections 110, 120 together form somewhat of a Vor Y shape as shown in FIGS. 1-2 when viewed from the lateral side(e.g., from the vantage of the customer 40 or the checkout clerk 38) andthus produces an open and airy architecture that is more inviting andmuch less bulky than a large enclosed tunnel structure. The openarchitecture structure or configuration also provides sight lines forthe customer to see customer's items passing through the read region.Nonetheless, access to items passing through the read region is stillinhibited by the general structure thereby enhancing security. This V orY-shaped structure with the dual arches produces this open architecturetunnel scanner, and at most may be described as semi-enclosed incontrast to an enclosed structure more akin to the airport carry-onluggage security checkpoint scanners.

Although the arch sections 110, 120 are illustrated as including an openspace between them, the arch sections 110, 120 may be embodied in anelongated tunnel formed over or around the conveyors 15/16. The portaldata reader 100 may thus be partially open and partially enclosed, suchas the example illustrated in FIG. 1, or fully enclosed such as via atunnel enclosure. The configuration of the dual arches 110, 120 createsan open architecture that provides some barrier/inhibition from acustomer reaching into the read zone and yet provides sight lines forallowing the customer to generally continuously observe items passingthrough the arches. A suitable portal scanner may be constructed withmore or less openness than the one illustrated. Additionally, a suitableportal scanner may be constructed, for example, with a single arch thathas similar functionality to the dual arch design described herein.

Though in the present descriptions the tunnel or portal scanner 100 maybe described in greater detail as an optical code reader, the scanner100 may alternately comprise an RFID reader, an image recognitionreader, an optical code reader, or combinations thereof.

Internal read optics will now be described in more detail. As previouslymentioned, internal read optics are disposed within (1) the arch legsections 112, 114, 122, 124, (2) the upper arch sections 116, 126, and(3) the drawer section 130 forming in combination an open dual-archstructure which will nonetheless be referred to as a tunnel scanner.Though the detailed example configuration of the tunnel/portal scannerwill be described as an imaging system comprised of fourteen cameraswith each camera having multiple views, other reading systemcombinations may be employed including other imaging configurations,laser reading systems, combinations thereof, or even including RFIDreaders.

The reading function from the arch leg sections will be described firstwith respect to FIGS. 4-12. Turning to FIG. 4, an optic set 150,including a camera and mirrors, is disposed within the first leg section112 of the front arch 110, producing an upper view segment or image path152 and a lower view segment or image path 154 into the read region. Theview segments 152, 154 are aimed or directed inwardly, upwardly andrearwardly into the read region for obtaining two-dimensional images ofview of customer side 36 and trailing side 32 of the item passingthrough the read region. Similarly, an optic set 160, including acamera, is disposed in the second leg section 124 in the rear arch 120,the camera and mirror set producing two fields of view into the readregion, namely an upper view segment or image path 162 and a lower viewsection or image path 164. The view segments 162, 164 are aimed ordirected inwardly, upwardly and forwardly into the read region forobtaining two-dimensional images of view of customer side 36 and leadingside 30 of the item passing through the read region.

FIG. 5 illustrates similar configurations for the camera optics in thesecond leg 114 of the front arch 110 and the first leg section 122 ofthe rear arch 120. An optic set 170, including a camera and mirrors, isdisposed within the second leg section 114 of the front arch 110,producing an upper view segment or image path 172 and a lower viewsegment or image path 174 into the read region. The view segments 172,174 are aimed or directed inwardly, upwardly and rearwardly into theread region for obtaining two-dimensional images of view of checker side34 and trailing side 32 of the item passing through the read region.Similarly, an optic set 180, including a camera and mirrors, is disposedin the first leg section 122 in the rear arch 120, the camera and mirrorset producing two fields of view into the read region, namely an upperview segment or image path 182 and a lower view section or image path184. The view segments 182, 184 are aimed or directed inwardly, upwardlyand forwardly into the read region for obtaining two-dimensional imagesof view of checker side 34 and leading side 30 of the item passingthrough the read region.

FIG. 6 is a diagram of a top view regarding the camera sectionsillustrated in FIGS. 4 and 5 and their crossing nature through the readregion. Specifically, optic set 150 within the first leg section 112 ofthe front arch 110; the optic set 170 in the second leg 114 of the frontarch 110; the optic set 160 in the second leg section of the rear arch120; and the optic set 180 in the first leg section of the rear arch120.

Details of the optic set and image view sections for the side legsections will now be described with reference to optic set 180 in thefirst leg section 122 of the rear arch 120 and with respect to FIGS.7-16. It should be understood that the description would be equallyapplicable to the other optic sets 150, 160, 170 adapted as needed tocreate image paths 152, 154, 162, 164, 172 and 174.

FIG. 7 is essentially a simplified version of FIG. 5 but showing onlythe optic set 180 in the first leg section of the rear arch 120, FIG. 8is a front side view of the optic set 180, and FIG. 9 is a top view ofthe optic set 180. The optic set 180 (including a camera and mirror set)is disposed in the first leg section 122 in the rear arch 120, thecamera and mirror set producing two fields of view into the read region,an upper view segment or image path 182 and a lower view section orimage path 184. The view segments 182, 184 are aimed or directedinwardly, upwardly and forwardly into the read region for obtainingtwo-dimensional images of view of checker side 34 and leading side 30 ofthe item 20 passing through the read region.

FIG. 10 illustrates both the upper view segment 182 and the lower viewsegment 184 produced from the optics set 180. FIG. 11 illustratesdetails of the optic set 180 that produces the lower view segment 184.Optic set 180 includes the camera along with the mirror sets. The cameracomprises an imager 192 mounted on an image board (PCB) 190 and thefocusing lens 194 for focusing the incoming image onto the imager 192.

Both the upper and lower image segments 182, 184 are imaged by the samecamera onto a common imager. In a preferred embodiment, the imagesegments 182, 184 are focused onto different regions of the image array.For purposes of description, each individual mirror component will beidentified with a unique identifying numeral (e.g., mirror 208) howeverin parentheses after certain of these numerals a mirror designation willbe at times provided in the form of M₁, M₂, M₃, etc. to describe themirror reflection order for that optical set. For a particular imageacquisition sequence, the designation M₁ would be the first mirrorclosest to the imager reflecting the image directly to the imager orimaging lens, M₂ would be the second mirror which would direct the imageto M₁, third mirror M₃ would be the mirror which directs the image tosecond mirror M₂, etc. Thus for an example five mirror system (M₁-M₅),the image from the read region would be reflected first by the fifthmirror M₅, which in turn reflects the image to fourth mirror M₄, whichin turn reflects the image to third mirror M₃, which in turn reflectsthe image to second mirror M₂, which in turn reflects the image to firstmirror M₁, which in turn reflects the image onto the imager.

Turning to FIG. 11 (and using this M₁, M₂, M₃, etc. naming convention),the image view segment 181 comprises the first view 181 a which isreflected by mirror 208 (M₅) with image segment 184 b then beingreflected by mirror 206 (M₄) with image segment 184 c then beingreflected by mirror 204 (M₃) as image segment 184 d which is in turnreflected by mirror 202 (M₂) from which view segment 184 e is thenreflected by mirror 200 (M₁) with image segment 184 f then being focusedby lens set 194 onto the imager 192. The lens set 194 may include anaperture and one or more lens elements.

In similar fashion with respect to FIG. 12, the view segment 182 has afirst image view segment 182 a which reflects off mirror 208 (M₄). It isnoted that mirror 208 producing the upper image view 182 is designatedas M₄ whereas in FIG. 11 for the lower view segment 184 mirror 208 isdesignated as mirror M₅ according to the convention. The image thenreflects off of mirror 208 (M₄) with segment 182 b then reflecting offof mirror 206 (M₃) with image segment 182 c then being reflected off ofmirror 210 (M₂) with image segment 182 d then reflecting off of mirror200 (M₁) which then reflects image segment 182 e back to imaging lens194 and onto (a region of) the imager 192.

FIGS. 13 and 14 are respective side views of the side leg imagers ofoptic set 180 with FIG. 13 illustrating the view path for image segment184 and FIG. 14 illustrating the view path for image segment 182. Theelements are the same as described in relation to FIGS. 11-12. FIGS.13-14 well illustrate the orientation of the first mirror 200. It isnoted here that the mirror 200 is a common mirror for both image views182 and 184 with one side of the mirror 200 reflecting the image view182 and the other side of the mirror 200 reflecting image view 184.

FIGS. 15 and 16 are respective top views of the side leg optic set 180with FIG. 15 illustrating the lower view segment 184 and FIG. 16illustrating the upper view segment 182. As shown in FIGS. 15 and 13,the image view segment 184 comprises the first image segment 184 a whichis reflected by mirror 208 (M₅) with image segment 184 b then beingreflected by mirror 206 (M₄) with image segment 184 c then beingreflected by mirror 204 (M₃) as image segment 184 d which is in turnreflected by mirror 202, (M₂) from which view segment 184 e is thenreflected by mirror 200 (M₁) with image segment 184 f then being focusedby lens 194 onto the imager 192 on image board 190. As shown in FIGS. 16and 14, the view segment 182 has a first image view segment 182 a whichreflects off mirror 208 (M₄) (it is noted that mirror 208 producing theupper image view 182 is designated as M₄ whereas in FIG. 11 for thelower view segment 184 mirror 208 is designated as mirror M₅). The imagethen reflects off of mirror 208 (M₄), then with image segment 182 breflecting off of mirror 206 (M₃), then with image segment 182 c beingreflected off of mirror 210 (M₂), then with image segment 182 dreflecting off of mirror 200 (M₁), which then reflects image segment 182e back to imaging lens and onto (another region of) the imager on imageboard 190. It is noted in a preferred construction that the upper viewsegment 182 is focused onto a first region of the imager 192 and thelower view segment 184 is focused onto a second (different) region ofthe imager 192.

FIGS. 17-22 illustrate optic sets and read regions for the top downreading sections out of the front arch top section 116 and the rear archtop section 126. Specifically in FIG. 17 the rear arch top section 126includes optic sets 250, 260, 270, 280. Each of these optic setsincludes a camera and respective reflecting mirrors for producing anupper view segment or image path and a lower view segment or image path.Specifically optic set 250 produces an upper view segment 252 and alower view segment 254 that project onto regions of a common imager ofthe camera. The views of the upper and lower view segments 252, 254 aredirected downward from the rear arch 120 and forwardly for readingoptical codes on the leading side 30 and top side 26 of the item 20passing through the read region. Similarly, optic set 260 produces anupper view segment 262 and lower view segment 264; optic set 270produces an upper view segment 272 and a lower view segment 274; andoptic set 280 produces an upper view segment 282 and a lower viewsegment 284. It is noted that these view segments, for example, viewsegments 252, 262, 272, 282 are arranged side by side and overlapping to(collectively) provide a continuous image view width-wise across theread region. It is noted that the upper view segments 252, 262, 272, 282are at a more forwardly facing angle than the lower view segments 254,264, 274, 284.

In similar fashion, as shown in FIGS. 18-20, a set of four optic sets300, 310, 320, 330 are disposed in the top arch section 116 of the frontarch 110. Specifically, the front arch top section 116 includes opticsets 300, 310, 320, 330. Each of these optic sets includes a camera andrespective reflecting mirrors for producing an upper view segment orimage path and a lower view segment or image path. Specifically opticset 300 produces an upper view segment 302 and a lower view segment 304that project onto regions of a common imager of the camera. The views ofthe upper and lower view segments 302, 304 are directed downward fromthe front arch 110 and rearwardly for reading optical codes on thetrailing side 32 and top side 26 of the item 20 passing through the readregion. Similarly, optic set 310 produces an upper view segment 312 andlower view segment 314; optic set 320 produces an upper view segment 322and a lower view segment 324; and optic set 330 produces an upper viewsegment 332 and a lower view segment 334. It is noted that these viewsegments, for example, view segments 302, 312, 322, 332 are arrangedside by side and overlapping to (collectively) provide a continuousimage view width-wise across the read region. It is noted that the upperview segments 302, 312, 322, 332 are at a more rearwardly facing anglethan the lower view segments 304, 314, 324, 334.

Details of the optic set and image view sections for each of the toparch sections 116, 126 will now be described with respect to optic set330, and with reference to FIGS. 21-22. It should be understood that thedescription would be equally applicable to the other optic sets 300,310, 320 in the top section 116 of the front arch 110 as well as theoptic sets 250, 260, 270, 280 in the rear arch top section 126.

FIG. 21 is a diagrammatic view primarily for showing the generaldirection of the upper view segment 332 relative to the lower viewsegment 334. FIG. 22 is a diagrammatic view of the optic set 330 asshown in FIG. 21 but on an enlarged scale with greater detail. Optic set330 includes a camera comprised of au imager 342 mounted on an imagerboard 340 and a lens set 343 including an aperture for focusing anincoming image onto the imager 342. The lower image view 334 includesthe first image segment 334 a which is reflected by a first mirror 344(M₁) downwardly to the lens set 343 where the image is captured on aregion of the imager 342. Thus the image view 334 is produced by asingle reflection. As visible in the diagrams of FIGS. 21-22, the imagesection 334 a is on one side (the left side) of the mirror 344.

The upper image view 332 is produced by a four mirror reflectionsequence. The upper image view 332 includes a first image view segment332 a which is reflected by a first mirror 348 (M₄), with second viewsegment 332 b then being reflected by second mirror 346 (M₃), with imagesegment 332 c then reflected by third mirror 345 (M₂), with image viewsegment 332 d then reflected by mirror 344 (M₁), with image segment 332e then focused by lens set 343 onto a region of imager 342. The mirror344 is a reflection mirror common to both the upper image view 332 andthe lower image view 334. The reflection portions of the mirror 344 foreach of the respective image views may be separate, but alternately maybe overlapping. It is noted in a preferred construction that the upperimage view 332 is focused onto a first region of the imager 342 and thelower image view 334 is focused onto a second (different) region of theimager 342. Alternately, the mirror 344 may be divided into separatemirrors, each of those separate mirrors providing the M₁ mirrorfunction. A window 117 is optionally provided in the lower surface ofthe arch section 116 for permitting passage of the image views 332 a,334 a into the interior of the arch section 116.

The previously-described sets of cameras in the arch sections 110, 120may be effective for collectively reading bar codes appearing on any ofthe upper five sides of the item 20 not obscured by the conveyor belt 15(namely the top side 26, leading side 30, customer side 36, trailingside 32 and checker side 34. In order to provide the capability ofreading bar codes on the bottom side 28, a bottom scanner function isprovided as will be illustrated with reference to FIGS. 23-31. Visibleon several of the figures, a gap 50 is provided between adjacent ends ofconveyor belts 15, 16. The gap 50 permits an opening through which thebottom scanner 400 may scan to read the bottom side 28 of the item 20 asthe item is passed over the gap 50. In a preferred configuration, thebottom scanner 400 includes two cameras 410, 420, situated side-by-side,each camera providing for half the length of the gap 50 between the sideleg sections 112, 114. As will be described, each camera 410, 420 isdivided into four separate linear scan views for its imager to providecoverage over the entire length of the gap 50. The length of the gap 50corresponds to the width of the conveyor belts 15, 16 between the sideleg sections 112, 114. As shown in FIGS. 25-26, the gap 50 formedbetween the first conveyor 15 and second conveyor 16 may include a slideplate (or slide plates) helping to the bridge the transition over thegap 50. FIGS. 25-26 show a pair of slide plates 52 a, 52 b with a smallopening 51 therebetween through which the various views from the camerasdisposed below may pass. FIG. 26 shows a gap 15 a between slide plate 52and conveyor belt 15 and gap 16 a between slide plate 52 b and conveyorbelt 16. Alternately the slide plates 52 a/52 b may comprise a singletransparent plate, or a single plate with a central transparent regionfor permitting passage of the images from the scanner 400 below. Thesurface of conveyor 15 is at a height h₁ higher than the surface of thedownstream conveyor 16. This height or step may provide for more smoothmovement of items across the gap 50, particularly larger items thatwould pass over the gap 50 without touching the plates 52 a/52 b.Details of the gap 50 and related components are further described inU.S. Application No. 61/435,744, filed on Jan. 24, 2011, herebyincorporated by reference.

As viewed in FIG. 24, the camera 410 includes an optic set which dividesthe view on its imager into four view sections namely two upwardly andrearwardly angled view sections 402, 404 passing through the left sideof the gap 50 and upwardly and forwardly slanted view sections 406, 408also spanning the left portion of the gap 50. Similarly, the camera 420has its view divided into four image segments with upwardly andforwardly directed views 412, 414 and upwardly and rearwardly directedviews 416, 418.

These view segments may alternately contain (a) a larger plurality ofimager rows (e.g., up to 200 rows or some other suitable numberdepending on optics and imager size) to create a relatively narrow view,(b) a few imager rows (e.g., 2 to 10 rows), or (c) a single imager rowto create a linear view. In a preferred configuration, each of the viewsegments is a relatively narrow, or nearly linear, scan through the gap50. Instead of generating what would be more of a two-dimensional view,a more linear read view plane may be generated through the gap 50 aimedsuch that the item being passed over the gap 50 is moved by theconveyors 15, 16 through the read plane. Considering an item 20 with abarcode on the bottom side 28, the camera takes a first linear image.Then the object/item is moved a certain distance and the process isrepeated (i.e., another linear image is acquired) generating a multitudeof linear images combined together resulting in a 2-D raster image. At agiven item velocity (as determined by the conveyor speed) and image viewrepetition rate, a given linear image spacing results, defining theresolution in this axis (along with the projected imager pixel size andthe imaging lens blur spot size). At a given scan rate, the faster theitem moves, the lower the resolution and the slower the item moves, thehigher the resolution (until limited by the resolution due to the pixelsize and the imaging lens blur function). Such a read mechanism isdescribed in U.S. Published Application No. US-2006-0278708 herebyincorporated by reference.

Details of the optic set for camera 420 will now be described withparticular reference to FIGS. 25-31. It should be understood that thedescription would be equally applicable in the optic set for camera 410.Camera 420 includes an imager 424 mounted on an imager board 422 with alens system 426 for focusing the image onto the imager 424. The imager424 comprises a two dimensional image array and accommodates multipleimage fields in the single array as shown in FIG. 31. Specifically, theimager 424 has four image regions or zones 424 a, 424 b, 424 c, and 424d. The image zones 424 a-424 d are separated by suitable gaps on the twodimensional image array 424. The imager 411 of camera 410 is of similarconfiguration.

FIG. 27 illustrates one side of the bottom reader generating the imageview 402 using the previously-described mirror order convention, theimage view 412 includes a first view segment 412 a which is reflected byfirst mirror 430 (M₄) directing second view segment 412 b onto secondmirror 432 (M₃), which directs third image segment 412 e onto thirdmirror 434 (M₂), which then directs fourth view segment 412 d ontofourth mirror 436 (M_(1a)), which then reflects fifth view segment 412 eto the camera 420 and imager 424 as focused by lens set 426. The imageview segment 412 e as laid out on the image array would for examplecorrespond to the imager zone section 424 b of FIG. 31.

FIG. 28 is a side view of the optic set of FIG. 24 also illustrating,the right side of the bottom reader generating the image view 413 usingthe previously-described mirror order convention in like mirrorconfiguration as the image view 412 illustrated in FIG. 27. The imageview 413 includes a first view segment 413 a which is reflected by firstmirror 440 directing second view segment 413 b onto second mirror 442,which directs third image segment 413 c onto a third mirror, which thendirects fourth view segment onto fourth mirror 446, which then reflectsfifth view segment 413 e to the camera and imager 424 as focused by lensset 426. The image view segment 413 e as laid out on the image arraywould for example correspond to the imager zone section 424 b of FIG.31.

FIG. 32 illustrates an alternate tunnel scanner 1000. The tunnel scannerarches 1010, 1020 of FIG. 32, spanning over the conveyor 1005 of thecounter section 1007, are shown with a greater angle and a largeropening in the central V shape structure. Such a design may provide forgreater openness to the structure, particularly to the center of thisalternate scanner 1000.

The configurations for the arch sections 110, 120, as described above,may provide sufficient height below the top cross-sections 116, 126 toaccommodate items of varying height as well as sufficient width betweenthe side leg sections 112, 114 to provide sufficient area to accommodateitems of expected width and height. The leg sections 112, 114 of thehousing for the tunnel scanner 100 may have curved or straight sections,or alternately angled as desired. FIG. 32 illustrates an alternatetunnel scanner 500. The tunnel scanner arches of FIG. 32 are shown witha greater angle and a larger opening in the central V shape structure.Such a design may provide for greater openness to the structure,particularly to the center of this alternate scanner 500.

As described above, the tunnel scanner 100 provides an arrangement of 14cameras (six cameras in each arch section 110, 120 and two cameras inthe bottom reader) with 32 unique images arranged out of the arches 110,120 and up through the gap 50. The relatively open architecture asformed by the back-to-back combination of separate arch sections 110,120 permits ambient light to reach into the inner read region. Sincethese arch sections 110, 120 provide a relatively open and non-enclosedstructure, this ambient light may be sufficient for illuminating thevarious other sides of the item 20 (other than potentially for thebottom side 28). Nonetheless, each image or view must have sufficientlight to illuminate the barcode and allow imaging and decoding.Therefore it may be preferable to provide separate illumination. Suchillumination should not have any direct internal reflections and shouldminimize specular reflections from products being scanned. Additionally,minimizing direct view of the lights by the user or customer isdesirable.

The illumination is organized into three separate regions, namely, toparch regions, side regions, and below the conveyor bottom region thatscans up through the gap 50. These illumination regions will beseparately described in following.

FIGS. 33-42 illustrate the various illumination sets disposed about thetunnel scanner housing. FIG. 33 is a rear side elevation view and FIG.34 is a diagrammatic cross-sectional side view of FIG. 33, these twofigures illustrating illumination sets in the rear arch top section 126and the rear arch first (left) leg section 122. Though only theillumination sets in the rear arch top section 126 and the rear archfirst leg section 122 are described, the illumination sets from theopposing leg sections and from the front arch top section 116 are oflike configuration and thus their descriptions are omitted for brevity.There are five illumination sets or modules 500, 510, 520, 530, 540arranged across the rear arch top section 126 (as shown in FIGS. 33-36).Each of the illumination modules includes three light emitting diodes(LEDs). As shown in the cross-sectional views of FIGS. 34 and 36, as anexample, illumination module 540 includes three LEDs 542, 544, 546,which in combination provide an overlapping illumination in a forwardly(upstream) and downwardly direction. The illumination set 540 isadjacent to the optic set 280 and provides in combination with theillumination set 530 on the opposite side of the optic set 280 arelatively diffuse and complete illumination for the image views 282,284 from optic set 280.

Similarly, illumination sets 530 and 520 are disposed on opposite sidesof optic set 270 for providing illumination for image views 272, 274;illumination sets 520, 510 on opposite sides of optic set 260 provideillumination for image views 262, 264; and illumination sets 510, 500 onopposite sides of optic set 250 provide illumination for image views252, 254. It is noted that for simplicity that optics sets 250, 260, 270are not shown in FIG. 33 and imaging optic sets 250 and 260 are notshown in FIG. 35, but the positioning of these optics sets would beunderstood with reference to prior figures (e.g., FIG. 17). Aspreviously mentioned, the optic modules 500, 510, 520, 530, 540 provideprimary illumination for the top side 26 as well as some illuminationfor the leading side 30 of the item 20.

FIG. 36 is a diagrammatic cross-section (on an enlarged scale) of therear arch top section 126 with the illumination set 540 comprised of theLEDs 542, 544, 546. LED 542 generates an illumination region or cone543; LED 544 produces an illumination region or cone 545; and LED 546produces an illumination region or cone 547. FIG. 36 also illustratesthe position of the illumination regions relative to the image views ofthe optic set 280. FIGS. 33-34 also illustrate the illumination from theside leg section 122. The upper illumination portion of the side legsection 122 includes illumination sets 550, 560, 570, 580 which as shownin FIGS. 33-34 and 37-42 project downwardly and laterally across theopening underneath the arch 126; and as best shown in FIG. 38 theillumination is directed forwardly from the rear arch 120. Such inwardand forward illumination direction is effective for illuminating thecustomer side 36 and the leading side 30 and to some degree the top side26 of the item 20 passing through the read region depending upon theitem's particular location and dimensions.

FIGS. 37-39 illustrate a first group of illumination sets and relativedirectional angles of the illumination cones with illumination set 550having illumination cone 552; illumination set 560 having illuminationcone 562; illumination set 570 having illumination cone 572; andillumination set 580 having illumination cone 582. It would be notedthat these cones are merely representations of illumination lightdirection as produced by the dual LED source of any particularillumination set. Each illumination set may be provided with a diffuseror focusing optics in order to diffuse or otherwise focus lightgenerated as desired. These cones in the drawings are merelyrepresentations of light emitted from the respective LED sets and arenot intended to be precise representations of light beams but areprovided to illustrate general light aiming direction and alignmentrelative to the view images from the cameras as previously described.

FIGS. 40-42 show the second group of illumination sets 600, 610, 620,630 disposed in the side leg 122. The direction of the light from thesecond group of LED sets 600, 610, 620, 630 is directed at a steeperdownward angle than that of the first group of illumination sets 550,560, 570, 580. In similar fashion, as previously described, illuminationset 600 includes two LEDs producing the downwardly directed illuminationcone 602; illumination set 610 produces downward illumination cone 612;illumination set 620 produces downward illumination cone 622; andillumination set 630 produces downward illumination cone 632. As shownin FIGS. 41-42, the illumination regions are formed in a somewhatadjacent and overlapping arrangement so as to provide a desired broadillumination pattern within the region. These illumination patterns 602,612, 622, 632 are effective for illuminating a top side 26, leading side30 and customer side 36 of an item 20 being passed through the readregion.

This combination of illumination sources provides a full illuminationacross the entirety of the width of the conveyor 15/16. Illuminationfrom the top arch sections 116, 126 is angled downwardly to concentrateat a far end of the field of view. As for the side illumination, all ofthe LEDs and lenses are placed outside the view of any direct windowreflection. Having the illumination direction of the LEDs generallydownward also helps avoid a specular reflection off shiny surfaces (suchas a soft drink can) and makes the direction of illumination lower thana typical adult eye level of a person standing to the side of the tunnelscanner 100 at the customer side, thus the likelihood of direct viewingof illumination by the customer is minimized. Furthermore, theillumination is generally aimed to the opposite side arm, thus blockingdirect view of the illumination from a human viewer.

The illumination LEDs are preferably pulsed and synchronized to a commontiming signal. Such synchronization minimizes motion blur and flicker.The illumination frequency is preferably greater than 60 Hz (or morepreferably on the order of 90 Hz) to avoid human flicker perception. TheLEDs in the arch sections 110, 120 are preferably full spectrum or whitelight LEDs configured to illuminate the scan volume with multiplewavelengths of light within a wavelength band of approximately (forexample) 380 nm to approximately 750 nm. Using white light allows thescanner illumination to also provide light for exception and securitycameras, if provided, and may provide a more pleasing natural lookingillumination, which may in turn improve device aesthetics.

Bottom illumination is provided from a set of two LEDs and an array ofcylinder lenses. FIG. 43 illustrates an example bottom illumination forone of the image planes 402 produced for each image plane by mirrors430, 432, 434, 436 focused by lens 426 into imager 424 (see furtherdetails of the imager in FIG. 27). Two illumination planes 704, 710 areproduced on opposite sides of the image plane 402 to provideillumination generally coextensive with the image plane 402 b. A firstset or row of LEDs 700 generates a diffuse plane of light that isfocused by cylinder lens 702 to form illumination plane 704 and a secondrow of LEDs 706 generates a diffuse plane of light that is focused bycylinder lens 708 to form illumination plane 710. A symmetric pair ofLED sets and cylinder lenses illuminate each of image views 404, 406,408, 412, 414, 416, 418. The bottom illumination does not contribute toexception imaging and thus can be of any color. Red LEDs may bepreferred, because of their increased efficiency and lower apparentbrightness to human observers, but other suitable colors such as whiteLEDs may be provided. The cylinder lens array provides two planes ofillumination for each side of a gap in the conveyer. The secondillumination line is aligned with the imager view approximately 50 mmabove the conveyor belt. Two illumination planes are used to maximizethe reading depth of field allowing for the fact that illuminationcannot readily be placed precisely on axis with the imager.

Though particular quantity of LEDs is illustrated and described for eachof the illumination sets (e.g., illumination set 540 has 3 LEDs;illumination set 550 has two LEDs), each of these illumination sets maycomprise one or more LEDs depending upon the desired intensity or otherpertinent design considerations.

Though the size and specifications of the imagers may depend on theparticular design, a preferred imager is a 1.3 megapixel CMOS imagerwith a resolution of 1280×1024 pixels. One preferred megapixel imager isthe model EV76C560 1.3MP CMOS image sensor available from e2V of Essex,England and Saint-Egreve, France. This imager may be applicable to thedata reader of any of the embodiments herein, however, any othersuitable types of imager of various resolutions may be employed.

The image field of the imagers need not be square or rectangular andmay, for example, be circular or have a profile of any suitablegeometric shape. Similarly, the image field regions need not be squareor rectangular and may, for example, have one or more curved edges. Theimage field regions may have the same or different sizes.

The focusing lenses that are proximate to the respective imagers, aswell as the path lengths of the respective image path segments mayprovide control for the depth of field for the respective image withinthe view volume.

The image captured by the image field may be processed as a singleimage, but preferably however, the image captured by each image fieldregion may be processed independently. The images from the differentperspectives of the object 20 may reach the image field regions with theobject being in the same orientation or in different orientations.Furthermore, the same image of the object 20 from the different (e.g.,mirror image) perspectives of the object 20 may reach the differentimage field regions or different images of the object 20 may reach thedifferent image fields. The different image field regions may have thesame photosensitivities or be receptive to different intensities orwavelengths of light.

The optics arrangements described above may contain additional opticalcomponents such as filters, lenses, or other optical components that maybe optionally placed in some or all of the image paths. The mirrorcomponents may include optical components such as surface treatmentsdesigned to filter or pass certain light wavelengths. In someembodiments, the image reflected by each mirror component can becaptured by the entire image field or read region when pulsed lightingand/or different wavelengths are used to separate the images obtained bythe different perspectives. The image reflection mirrors preferably haveplanar reflecting surfaces. In some embodiments, however, one or morecurved mirrors or focusing mirrors could be employed in one or more ofthe imaging paths provided that appropriate lenses or image manipulatingsoftware is employed. In some embodiments, one or more of the mirrorsmay be a dichroic mirror to provide for selective reflection of imagesunder different wavelengths.

The mirrors may have quadrilateral profiles, but may have profiles ofother polygons. In some preferred embodiments, one or more of themirrors have trapezoidal profiles. In some alternative embodiments, oneor more of the mirrors may have a circular or oval profile. The mirrorsmay have dimensions sufficient for their respective locations topropagate an image large enough to occupy an entire image field of arespective imager. The mirrors may also be positioned and havedimensions sufficiently small so that the mirrors do not occlude imagesbeing propagated along any of the other image paths.

In some embodiments, the imagers may all be supported by or integratedwith a common PCB or positioned on opposing sides of the common PCB. Insome embodiments, the common PCB may comprise a flexible circuit boardwith portions that can be selectively angled to orient some or all ofthe imagers to facilitate arrangements of image paths.

In one example, the imagers may be selected with a frame rate of 30 Hzand one or more of the light sources used to illuminate the read regionare pulsed at 90 Hz. Examples of light source pulsing is described inU.S. Pat. No. 7,234,641, hereby incorporated by reference.

In addition to the variations and combinations previously presented, thevarious embodiments may advantageously employ lenses and light baffles,other arrangements, and/or image capture techniques disclosed in US.Pat. Pub. No. 2007/0297021, which is hereby incorporated by reference.

A fixed virtual scan line pattern may be used to decode images such asused in the Magellan-1000i model scanner made by Datalogic ADC, Inc.(previously known as Datalogic Scanning, Inc.) of Eugene, Oreg. In someembodiments, an alternative technique based on a vision library may beused with one or more of the imagers.

In order to reduce the amount of memory and processing required todecode linear and stacked barcodes, an adaptive virtual scan line (VSL)processing method may be employed. VSLs are linear subsets of the 2-Dimage, arranged at various angles and offsets. These virtual scan linescan be processed as a set of linear signals in a fashion conceptuallysimilar to a flying spot laser scanner. The image can be deblurred witha one dimensional filter kernel instead of a full 2-D kernel, therebyreducing the processing requirements significantly.

The rotationally symmetric nature of the lens blurring function allowsthe linear deblurring process to occur without needing any pixelsoutside the virtual scan line boundaries. The virtual scan line isassumed to be crossing roughly orthogonal to the bars. The bars willabsorb the blur spot modulation in the non-scanning axis, yielding aline spread function in the scanning axis. The resulting line spreadfunction is identical regardless of virtual scan line orientation.However, because the pixel spacing varies depending on rotation (a 45degree virtual scan line has a pixel spacing that is 1.4× larger than ahorizontal or vertical scan line) the scaling of the deblurringequalizer needs to change with respect to angle.

If the imager acquires the image of a stacked barcode symbology, such asGSI DataBar (RSS) or PDF-417 code, the imaging device can start with anomnidirectional virtual scan line pattern (such as an omnidirectionalpattern) and then determine which scan lines may be best aligned to thebarcode. The pattern may then be adapted for the next or subsequentframe to more closely align with the orientation and position of thebarcode such as the closely-spaced parallel line pattern. Thus thedevice can read highly truncated barcodes and stacked barcodes with alow amount of processing compared to a reader that processes the entireimage in every frame.

Partial portions of an optical code (from multiple perspectives) may becombined to form a complete optical code by a process known asstitching. Though stitching may be described herein by way of example toa UPCA label, one of the most common types of optical code, it should beunderstood that stitching can be applied to other types of opticallabels. The UPCA label has “guard bars” on the left and right side ofthe label and a center guard pattern in the middle. Each side has 6digits encoded. It is possible to discern whether either the left halfor the right half is being decoded. It is possible to decode the lefthalf and the right half separately and then combine or stitch thedecoded results together to create the complete label. It is alsopossible to stitch one side of the label from two pieces. In order toreduce errors, it is required that these partial scans include someoverlap region. For example, denoting the end guard patterns as G andthe center guard pattern as C and then encoding the UPCA label012345678905, the label could be written as G012345C678905G.

Stitching left and right halves would entail reading G012345C andC678905G and putting that together to get the full label. Stitching aleft half with a 2-digit overlap might entail reading G0123 and 2345C tomake G012345C. One example virtual scan line decoding system may outputpieces of labels that may be as short as a guard pattern and 4 digits.Using stitching rules, full labels can be assembled from pieces decodedfrom the same or subsequent images from the same camera or piecesdecoded from images of multiple cameras. Further details of stitchingand virtual line scan methods are described in U.S. Pat. Nos. 5,493,108and 5,446,271, which are hereby incorporated by reference.

In some embodiments, a data reader includes an image sensor that isprogressively exposed to capture an image on a rolling basis, such as aCMOS imager with a rolling shutter. The image sensor is used with aprocessor to detect and quantify ambient light intensity. Based on theintensity of the ambient light, the processor controls integration timesfor the rows of photodiodes of the CMOS imager. The processor may alsocoordinate when a light source is pulsed based on the intensity of theambient light and the integration times for the photodiode rows.

Depending on the amount of ambient light and the integration times, thelight source may be pulsed one or more times per frame to createstop-motion images of a moving target where the stop-motion images aresuitable for processing to decode data represented by the moving target.Under bright ambient light conditions, for example, the processor maycause the rows to sequentially integrate with a relatively shortintegration time and without pulsing the light source, which creates aslanted image of a moving target. Under medium light conditions, forexample, the rows may integrate sequentially and with an integrationtime similar to the integration time for bright ambient light, and theprocessor pulses the light source several times per frame to create astop-motion image of a moving target with multiple shifts betweenportions of the image. The image portions created when the light pulsesmay overlie a blurrier, slanted image of the moving target. Under lowlight conditions, for example, the processor may cause the rows tosequentially integrate with a relatively long integration time and maypulse the light source once when all the rows are integrating during thesame time period. The single pulse of light creates a stop-motion imageof a moving target that may overlie a blurrier, slanted image of themoving target.

In some embodiments, a data imager contains multiple CMOS imagers andhas multiple light sources. Different CMOS imagers “see” different lightsources, in other words, the light from different light sources isdetected by different CMOS imagers. Relatively synchronized images maybe captured by the multiple CMOS imagers without synchronizing the CMOSimagers when the CMOS imagers operate at a relatively similar framerate. For example, one CMOS imager is used as a master so that all ofthe light sources are pulsed when a number of rows of the master CMOSimager are integrating.

Another embodiment pulses a light source more than once per frame.Preferably, the light source is pulsed while a number of rows areintegrating, and the number of integrating rows is less than the totalnumber of rows in the CMOS imager. The result of dividing the totalnumber of rows in the CMOS imager by the number of integrating rows isan integer in some embodiments. Alternatively, in other embodiments, theresult of dividing the total number of rows in the CMOS imager by thenumber of integrating rows is not an integer. When the result ofdividing the total number of rows in the CMOS by the number ofintegrating rows is an integer, image frames may be divided into thesame sections for each frame. On the other hand, when the result ofdividing the total number of rows in the CMOS by the number ofintegrating rows is not an integer, successive image frames are dividedinto different sections.

Other embodiments may use a mechanical shutter in place of a rollingshutter to capture stop-motion images of a moving target. The mechanicalshutter may include a flexible member attached to a shutter that blockslight from impinging a CMOS or other suitable image sensor. The shuttermay be attached to a bobbin that has an electrically conductive materialwound around a spool portion of the bobbin, where the spool portionfaces away from the shutter. The spool portion of the bobbin may beproximate one or more permanent magnets. When an electric current runsthrough the electrically conductive material wound around the spool, amagnetic field is created and interacts with the magnetic field from theone or more permanent magnets to move the shutter to a position thatallows light to impinge a CMOS or other suitable image sensor.

These and other progressive imaging techniques are described in detailin U.S. Published Patent Application No. US-2010-0165160 entitled“SYSTEMS AND METHODS FOR IMAGING” hereby incorporated by reference.

The system of the tunnel/portal scanner 100 preferably includes anobject measurement system and related software that uses dead reckoningto track the position of items through the read region. Details of theobject measurement system are further described in U.S. Application No.61/435,686 filed Jan. 24, 2011 and U.S. Application No. 61/505,935 filedJul. 8, 2011, hereby incorporated by reference. The software of theobject measurement system records the times an item passes a leadinglight curtain 805 a (at the upstream end of the front arch 110), asshown in FIGS. 50-52 and a trailing light curtain 805 b (at thedownstream end of the rear arch 120) or is detected by sensors (e.g.,positioning sensors) and assumes a constant known velocity of theconveyors 15, 16. In one embodiment, the leading and trailing lightcurtains 805 a, 805 b are formed by sensor elements 5010 positionedvertically along arch leg sections 112, 114, 122, 124. When an itempasses through the leading and trailing light curtains 805 a, 805 b,certain ones of the sensor elements 5010 are blocked dependent on theheight (H) of the item. Multiple reads of the sensor elements providelight curtain data corresponding to a vertical object sensor (VOS)profile that represents the height and longitudinal length (L) of theitem. The object measurement system also includes one or more lateralobject sensors 5300 a, 5300 b positioned under conveyors 15, 16 thatview the item through gap 50 as shown in FIGS. 53-55. For example,lateral object sensor 5300 a produces a rearward directed view 5310 aand the lateral object sensor 5300 b produces a forward directed view5310 b. In one embodiment, lateral object sensors 5300 a, 5300 bcorrespond to the cameras 410, 420 of the bottom scanner 400. In anotherembodiment, lateral object sensors 5300 a, 5300 b may have associatedilluminators 711 a, 711 b and may be separate from the cameras 410, 420.As the item passes over gap 50, the lateral object sensor(s) (eithersensor 5300 a or sensor 5300 b or both) measures the footprint (e.g.,longitudinal length and lateral width) of the item to produce lateralobject sensor data corresponding to a lateral object sensor (LOS)profile. The VOS profile and the LOS profile are combined by the objectmeasurement system to produce model data representing athree-dimensional model of the item.

When an item is scanned and decoded, the model data (produced asdescribed above) is combined with the timing and trajectory of thedetected barcode to correlate barcode data with the three-dimensionalmodel of the item at an estimated item position. The correlation allowsthe tunnel/portal scanner to differentiate between multiple reads of thesame item, and distinguish identical labels on multiple items. Deadreckoning may also allow the software to determine the presence ofmultiple distinct labels on individual items (such as an overpack labelfor a multi-pack of items).

As described above, the tunnel scanner 100 employs a plurality of 14cameras, with some of the cameras (the top and side cameras) each havingtwo image views on its imager and other cameras (the bottom cameras)each having four image views on its imager. FIG. 44 illustrates anexemplary system architecture 800 for the tunnel scanner 100. Imagesfrom the cameras in each scanner are decoded and the decoded information(decode packets and lateral sensor packets (e.g., information fromlateral object sensors 5300 a, 5300 b)) is sent to the interconnectprocessor 810. Light curtain information from the light curtains 805 a,805 b (pertaining to the size and position of item being passed throughthe read region) is processed and the corresponding information (lightcurtain state packets) is also sent to the interconnect processor 810.The interconnect processor 810 applies time stamps to the packets andsends the time stamped packet data to the correlation processor 812. Thecorrelation processor 812 generates object models (e.g.,three-dimensional models of objects) from the light curtain and lateralsensor packets and correlates object data with the decode packets todetermine which objects correspond to the decoded data. Successfullycorrelated barcode information as well as exception data is thentransmitted to the POS host. Exception data corresponds to any number ofevents when the object models and decode packets indicate that an errormay have occurred. Examples of exceptions include, but are not limitedto: (a) more than one barcode is correlated with an object; and (2) nobarcode is correlated with an object model; (3) a barcode is read but isnot correlated with an object model.

FIG. 45 is a flow chart of a side scanner and top scanner decodeprocessor algorithm 820 according to one embodiment, having thefollowing steps:

Step 822—configuring camera for triggered mode.

Step 824—checking for synchronization signal from interconnectprocessor.

Step 826—if synchronization signal is detected, (Yes) proceed to Step828; if No, return to Step 824.

Step 828—capturing image (trigger the camera to capture an image).

Step 830—reading out image from the imager into processor memory imagebuffer.

Step 832—processing image to locate and decode barcodes in image buffer.The image may be processed using a suitable image processing algorithm.

Step 834—determining whether a barcode was successfully decoded: if Yes,proceed to Step 836, if No, return to Step 824 to process additionalimages. For each barcode found in image buffer, record the symbologytype (UPC, Code 39, etc), decoded data, and coordinates of the boundingbox corners that locate the decoded label in the image.

Step 836—creating decode packet (with the recorded symbology type,decoded data and coordinates).

Step 838—sending recorded data (decode packet) to the interconnectprocessor and then returning to Step 824 to process additional images.

FIG. 46 is a flow chart of a bottom scanner decode processor algorithm840 according to an embodiment, having the following steps:

Step 842—Configuring the camera to continuously capture images and readout 4 rows of data. In a preferred reading method, the frame rate ofreading out frames of 4 rows each is 2.5 KHz (2500 frames/second).

Step 844—Setting decode and lateral sensor counters to zero.

Step 846—Setting L to equal the desired periodicity for creation oflateral sensor packets. In one example the value of L=20.

Step 848—capturing image and reading out each of the 4 rows of data fromthe lager (imager 411 or 424) into a temporary buffer.

Step 850—storing each row of data into one of four circular imagebuffers containing 2N rows to generate four separate linescan images inprocessor memory.

Step 852—increment decode and lateral sensor counters.

Step 854—Determining if decode counter=N: if Yes proceed to Step 856; ifNo proceed to Step 862. N represents how tall the decode buffer is. Inone example, N=512, which corresponds to about 2.5 inches of beltmovement (e.g., belt speed of 12 inches/sec, divided by a line scanspeed of 2500 Hz times N of 512 equals 2.5 inches).

Step 856—Processing each of the 4 image buffers sequentially (using theimage processing algorithm) to locate and decode barcodes. The imageprocessing algorithm analyzes an image using horizontal and verticalscan lines to find start and/or stop patterns of an optical code. Thealgorithm then traverses the image roughly in the direction of theoptical code (also moving in a transverse direction as necessary) todecode the digits of the optical code similar to an adaptive VSLalgorithm.

Step 858—creating a decode packet if the decode is successful. If thenumber of rows in the circular buffer is 2N, then for every N rows, animage of the previous 2N pixels is decoded as a frame. For each barcodefound in image buffer, record the symbology type (UPC, Code 39, etc),decoded data, and coordinates of the bounding box corners that locatethe decoded label in the image. The recorded symbology type, decodeddata and coordinates constitute the decode packet.

Step 860—setting decode counter to zero. The decode counter represents avariable that counts the number of rows that have been put into thecircular buffer.

Step 862—determining if lateral sensor counter=L: if Yes, proceed toStep 864; if No, proceed to Step 868. L represents the number of rows toskip between outputting lateral sensor data. In one example, theresolution of the lateral object sensors 5300 a, 5300 b is about 5 mils(e.g., 12 inches/sec divided by 2500 Hz). An L value of 20 provides aspacing of the lateral sensor data of about 0.1 inch.

Step 864—creating lateral sensor packet. As an example, periodically(for example every 20 rows of data captured) a lateral sensor packet iscreated by: selecting a subset of the columns in the 4 rows of data(e.g., every 20 columns) and binarizing the data by comparing the pixelintensity to a fixed threshold. This creation of the lateral sensorpacket process provides a coarse resolution binary representation of theobjects passing by the bottom scanner. This binary representationcorresponds to a footprint of the object. For any object viewable by thelateral object sensor, the object's longitudinal length is determined bythe number of rows in the object footprint multiplied by the objectfootprint pixel size.

Step 866—setting lateral sensor counter to zero.

Step 868—sending recorded data (decode packets and lateral sensorpackets) to the interconnect processor and then returning to Step 848 tocapture/read out more images.

FIG. 47 is a flow chart of a light curtain processor algorithm 870according to an embodiment, having the following steps:

Step 872—checking for synchronization signal for the interconnectprocessor. The light curtain sensor elements 422 are monitored todetermine the height of an object. For example, an object's height isdetermined by tallest light curtain sensor element that was blocked whenthe object is passed by. The light curtain sensor elements 422 may alsobe used to determine the longitudinal length of the object. For example,for objects tall enough to block at least one beam in the light curtain,object length is determined by time difference (as measured by FrameCount difference) between trailing light curtain being first blocked tobeing unblocked multiplied by assumed object velocity (typically theconveyor belt velocity).

Step 874—monitoring light curtain beams and waiting for a change ofstate (where a beam is just interrupted or just cleared).

Step 875—determining if a change of state has not occurred: if No,returning to Step 872; if Yes, proceeding to Step 876.

Step 876—creating light curtain state packet that represents the currentlight curtain state (e.g., corresponding to a bit pattern (for example,1=vertically aligned sensors blocked, 0=vertically aligned sensorsunblocked)).

Step 878—transmitting light curtain state packet (indicating currentstate of light curtain beams) to the interconnect processor and thenreturning to Step 872.

FIG. 48 is a flow chart of an interconnect processor algorithm 880according to an embodiment, having the following steps:

Step 882—Generating a periodic synchronization signal and sending it tothe decode processors. This periodic synchronization signal sets theframe rate of the system. In a preferred example herein, periodicsynchronization signal is 30 Hz (30 frames/second).

Step 884—incrementing a counter (a frame count) each time thesynchronization pulse is emitted. In one example, the synchronizationpulse is emitted periodically at 30 Hz.

Step 886—determining whether data is available: if No, returning to Step882; if Yes, proceeding to Step 888.

Step 888—receiving decode packets from the top, side, and bottom decodeprocessors.

Step 888 (cont'd)—receiving lateral sensor packets from the bottomdecode processors and the light curtain state packets from the lightcurtain processor.

Step 890—recording the decode packets and the lateral sensor packets andrecording the value of the frame count when the packets were received(referred to as time stamping of the packets).

Step 892—sending the time stamped packet data to the correlationprocessor.

FIG. 49 is a flow chart of an example correlation processor algorithm900 according to an embodiment, having the following steps:

Step 902—waiting to receive packets (i.e., the lateral sensor packetsfrom the bottom decode processors and the light curtain state packetsfrom the light curtain processor) from the interconnect processor.

Step 904—generating a three-dimensional object model (e.g., from anobject footprint and side profile (LOS and VOS profiles)) from the lightcurtain state packets and lateral sensor packets. An object model is avolume solid with base equivalent to the object footprint, or simplifiedrepresentation thereof (such as a rectangle) and a height as measured bythe light curtain sensor data.

Step 906—determining if the object has left the read region: if No,return to Step 902; if Yes, proceeding to Step 908. Whether the objecthas left the read region may be determined in various ways. For example,the light curtain state packet or lateral sensor packet may indicatethat an object has left the scan volume. In one example, transition ofthe trailing light curtain from a blocked state to an unblocked stateindicates that an object has left the scan volume. In other examples,the leading light curtain and/or the lateral object sensor may be usedto determine when an object leaves the read region. If data from theleading light curtain or lateral object sensor is used, the location ofthe object model is translated by the distance between the locations ofthe leading light curtain (and/or lateral object sensor) and thetrailing light curtain so that the object model is at the edge of thetrailing light curtain.

Step 908—analyzing decode packet locations to determine if any of thelocations correspond to the object. For example, a decode trajectory ora back projection ray is generated for each decode packet by consideringthe camera parameters of the camera that decoded the barcode andbounding box coordinates. Generation of back projection rays is furtherdiscussed in U.S. Patent Application Nos. 61/435,686 and 61/505,935,incorporated by reference above. Back projection rays are translated bythe assumed movement of the object that would have occurred from thedecode time until the present moment (by computing the time differenceas measured by frame count difference between the moment the object leftthe scan volume and the moment when the decode occurred). After the backprojection rays are translated, it is determined whether any backprojection rays intersect the object model.

Step 910—transmitting optical code data and exception information tohost processor. If a single barcode value is associated with an object,a “Good Read” indication may be sent to the host processor. Theexception information may correspond to one or more of variousexceptions. In one example, the exception information may indicate thatmultiple different barcode values are associated with an object (e.g., a“Multiple Barcode Read” exception). In another example, the exceptioninformation may indicate that an object as seen but no barcode wasassociated with it (e.g., a “No Read” exception). In another example,the exception information may indicate that a barcode was decoded but noobject was associated with it (e.g., a “Phantom Read” exception).

It is intended that subject matter disclosed in portion herein can becombined with the subject matter of one or more of other portions hereinas long as such combinations are not mutually exclusive or inoperable.In addition, many variations, enhancements and modifications of theimager-based optical code reader concepts described herein are possible.

The terms and descriptions used above are set forth by way ofillustration only and are not meant as limitations. Those skilled in theart will recognize that many variations can be made to the details ofthe above-described embodiments without departing from the underlyingprinciples of the invention.

The invention claimed is:
 1. A scanning system for reading optical codeson items being passed via a transport mechanism through a read volume ofthe system, comprising a front arch section and a rear arch section,each arch section having (a) first and second lateral leg sections, and(b) a top arch section connected to a top portion of each of the firstand second lateral leg sections and spanning therebetween over a widthof the transport mechanism, wherein the front arch section and thesecond arch section are arranged with lower portions of the front archlateral leg sections adjacent to lower portions of the rear arch lateralleg sections, wherein the front arch section is slanted forwardly andthe rear arch section is slanted rearwardly; a plurality of readersdisposed in the top arch sections and the lateral leg sections forreading an optical code on any of five sides of a six-sided box-shapeditem being passed through a read region formed by the arch sections. 2.A system according to claim 1 wherein the plurality of readers comprisescameras disposed in the lateral side legs and the arch top sections, oneor more of the cameras each having an imager, a lens system andassociated mirrors for forming multiple image views on the imager.
 3. Asystem according to claim 2 further comprising a plurality ofillumination modules disposed in the first and second arch sections,each module including one or more light emitting diodes (LEDs) forprojecting an illumination region into the read region, the illuminationmodules providing illumination for the image views of the item beingpassed through the read region.
 4. A system according to claim 1 whereinthe front arch section and the rear arch section are of likeconfiguration.
 5. A system according to claim 4 wherein the front archsection and the rear arch section are arranged back-to-back.
 6. A systemaccording to claim 4 wherein the front arch section comprises aninverted U-shaped housing.
 7. A system according to claim 1 furthercomprising a chassis, wherein the first and second arch sections aremounted to and aligned by the chassis.
 8. A system according to claim 1wherein the transport mechanism comprises a conveyor and the systemfurther comprising a first conveyor section and a second conveyorsection with a gap formed between the first and second conveyorsections; a bottom scanner disposed below the conveyor reading upthrough the gap to read optical codes on a bottom side of items as theypass over the gap.
 9. A system according to claim 8 further comprising adrawer slidably mounted below the conveyor, wherein the bottom scanneris disposed in the drawer.
 10. A system according to claim 9 furthercomprising a chassis, wherein the first and second arch sections and thedrawer are mounted to and aligned by the chassis.
 11. A system accordingto claim 1 wherein the scanning system is configured in the form of atunnel or portal scanner.
 12. A method for reading an optical codecomprising the steps of moving an item bearing an optical code through aread region of a tunnel or portal scanner via a transport mechanism;providing an open architecture scanner housing comprising front and rearinverted U-shaped arch sections separated by an opening between topsections thereof; forming a read region under and between the archsections by positioning a plurality of imagers in each of the front andrear arch sections and directing fields of view into the read region toproduce views of front, rear, top, left lateral and right lateral sidesof a six sided box-shaped item being passed through the read region;forming images at the imagers from the fields of view; processing theoptical code based on one or more of the images.
 13. A method accordingto claim 12 wherein the transport mechanism comprises a conveyor, themethod further comprising providing the conveyor with first and secondconveyor sections separated by a relatively narrow gap therebetween; viathe conveyor, passing the item from the first conveyor section to thesecond conveyor section over the gap; directing one or more fields ofview upwardly through the gap from one or more imagers located below theconveyor to produce a view of a bottom side of the six sided box-shapeditem being passed over the gap.
 14. A method according to claim 12further comprising illuminating the read region with a plurality ofillumination modules, the illumination modules being arranged in variouslocations about the arch sections with each illumination moduleprojecting illumination along one of the fields of view of one of theimagers.
 15. A method according to claim 12, wherein each arch sectionincludes (a) first and second lateral leg sections, and (b) a top archsection connected to a top portion of each of the first and secondlateral leg sections and spanning therebetween over a width of theconveyor, the method further comprising projecting fields of view out ofeach of: the top arch section, the first lateral leg section and thesecond lateral leg section.
 16. A method according to claim 12 furthercomprising arranging the front arch section and the second arch sectionback-to-back with the front arch section slanted forwardly and the reararch section slanted rearwardly
 17. A method according to claim 12,wherein the arch sections together forming a V or Y shape as viewed froma lateral side.
 18. An automated checkout system for reading items, theautomated checkout system comprising: a portal scanner having an openarchitecture scanner housing comprising front and rear inverted U-shapedarch sections adjacently arranged with an opening between top sectionsthereof; a conveyor operable to receive and transport an item along apath through a read zone of the portal scanner.
 19. An automatedcheckout system according to claim 18 further comprising a conveyorcomprising a leading conveyor section and a trailing conveyor sectionspaced apart from the leading conveyor section by a gap such that theitem is transportable across the gap from the leading conveyor sectiononto the trailing conveyor section; a data reader positioned beneath theconveyor and oriented to read encoded data on a bottom side of the itemthrough the gap.
 20. An automated checkout system according to claim 18wherein the portal scanner comprises a front arch section and a reararch section, each arch section having (a) first and second lateral legsections, and (b) a top arch section connected to a top portion of eachof the first and second lateral leg sections and spanning therebetweenover a width of the conveyor, wherein the front arch section and thesecond arch section are arranged back-to-back with lower portions of thefront arch lateral leg sections adjacent to lower portions of the reararch lateral leg sections, wherein the front arch section is slantedforwardly and the rear arch section is slanted rearwardly.
 21. Anautomated checkout system according to claim 18 wherein the portalscanner comprises a data reader selected from the group consisting of:an optical code reader; an RFID reader; an image recognition reader; andcombinations thereof.